The present invention relates generally to the field of semiconductors, and more particularly to Titanium Oxide film.
Atomic layer deposition (ALD) is a vapor phase thin film deposition technique that has gained considerable popularity in recent years. The following list of ALD benefits goes a long way towards explaining the broad popularity of the technique (i) wide range of materials available including oxides, nitrides, sulfides, fluorides, metals, ternaries, quaternaries, chalcogenides, etc., (ii) digital film thickness control with Angstrom level resolution, (iii) excellent film uniformity even over large substrate sizes, (iv) relatively low deposition temperatures with some processes available at room temperature allowing deposition on temperature sensitive substrates such as plastics (especially when deposition is plasma enhanced), (v) moderate vacuum levels with some processes available at atmospheric pressure, (vi) conformal coatings on high aspect ratio topographies, (vii) excellent film adhesion to underlying substrates, (viii) ability to mix different film chemistries to gain the advantages of doping and laminates, and (ix) relatively simple hardware compared to other thin film deposition techniques.
Atomic Layer Deposition (ALD) and/or Plasma Enhanced Atomic Layer Deposition (PEALD) titanium oxide (TiOx) can be used as a spacer material, especially for back end of line (BEOL) sidewall image transfer (SIT) patterning. Titanium Oxide has potential benefit over SiO2 spacer due to less spacer erosion and high selectivity during subsequent etch. But Titanium Oxide spacer film gets modified during spacer etch back/mandrel removal using F and Cl based chemistry, and once modified the spacer materials have high wet etch rate in common wet clean solutions (HF, HCl, polyacrylamide (PAM), and/or standard cleans (SC) 9SC-1 and/or SC-2). However, this leads to an increase in spacer loss and critical dimension (CD) blow out during the wet clean processing. Additionally, scanning transmission electron microscope (STEM) comparison after wet etching show blanket data for higher thickness loss was confirmed, demonstrating a need to improve this CD bias post wets.